The IPS type liquid crystal display device is configured that the electric field for driving the liquid crystal layer is directed to be in substantially parallel with a principal plane of a TFT substrate (in a horizontal direction) so that the viewing angle is wider than that of the twisted nematic (TN) type for driving the liquid crystal layer in the longitudinal electric field.
Although the IPS type liquid crystal display device provides the wide viewing angle, the planar configuration of electrodes has the small aperture ratio, resulting in the problem of low transmittance. The wall electrode IPS type liquid crystal display device has been proposed for coping with the aforementioned problem (JP-A-6-214244, JP-A-6-332014, JP-A-11-231344, and Proceedings of China Display/Asia Display 2011, P2-23, pp. 597-600). The wall electrode IPS type liquid crystal display device is designed to have the electrode with the wall-like structure. The aforementioned device includes two types, one is configured to form the electrode itself into the wall-like structure, and the other is configured to form the electrode on the side wall of the wall-like insulating film. Any of those types allows the electrode to keep a substantial area while reducing the area on the plane to maintain the aperture ratio, as well as improve the transmittance.